Convective cooling of continuously moving metal strip



Jan. 7, 1964 D. BEGGS ETAL 3,116,788

CONVECTIVE COOLING OF CONTINUOUSLY MOVING METAL STRIP 4 Sheets-Sheet l Filed July 13, 1961 INVENTORS.' amzld egg-f, Larrqlg 0one, 'lnyj Yaung Phill/11.161151:

IE-l- ATTORNEY Jan. 7, 1964 Filed July 13, 1961 D. BEGGS ETAL 3,116,788

OONvEcTIvE COOLING OF OONTINUOUSLY MOVING METAL STRIP ATTDRNEY Jan. 7, 1964 D. BEGGS ETAL 3,116,738

ooNvEcTIvx-I COOLING oF coNTINUoUsLY MOVING METAL STRIP v Filed July l5, 1961 4 Sheets-Sheet 5 TIE- L- INVENTORS: amzld Be gs, 'arrall dane,

ATToRIvIY Janf. 7, 1964 D.' BEGGS ETAL 3,116,788

coNvEcTIvE VCOOLING oF coNTINuoqsLy MOVING METAL. STRIP Filed July 15, 1961 4 Sheets-Sheet 4 ATTORNEY United States Patent O Donald Boggs and Carroll Cone, Toledo, Ghia, Gloyd H. Young, lds, Mich., 'and Philip l... Knight, Toledo, (Ehio, assigner-'s to Midland-Ross Corporation, Toledo, Uhio, a corporation of @hie Filed duly i3, wel, Ser. No. l23,373 l Claims. (6l. 16S-12d) This invention relates to the art of heat treating metal strip. More particularly, the invention relates to improved apparatus for accomplislng the controlled cooling of metal strip from high temperature by means of high convection heat transfer to a cooling fluid. The invention is particularly well suited for a strip processing unit in which the strip is passed through the unit in one or more vertically travelling passes.

lt has heretofore been the practice in the cooling of metal strip by convective heat transfer to a cooling lluid to pass the cooling lluid in a direction parallel to the moving strip either in parallel flow or in counterilow heat transfer relationship therewith. lt has recently been discovered, however, that the worlr can be cooled considerably more rapidly if the cooling fluid is directed in jets against the work, the jets having a substantial component of motion directed perpendicularly to the strip. Because or" certain problems associated with prior art iet cooling arrangements, however, the concept of jet cooling heretofore has not gained widespread acceptance and prior artisans have, in general, exhibited a preference for radiation cooling arrangements, such as that illustrated in Patent 2,983,497 to Dailey, l r., and for parallel iiow convection cooling arrangements such as that described in Canadian Patent 613,946.

The jet cooling arrangement heretofore found most preferable by prior artisans, at least in cooling units having a plurality of passlines, comprises a plenum chamber (or a plurality of plenum chambers arranged in a vertical colurnn) disposed between adjacent passlines of the cooling chamber. Associated with each cooling chamber is a. circulating fan which circulates protective atmosphere into the plenum chamber from whence it passes through ports on either side thereof outwardly against passes of strip moving along the passlines of the cooling unit. After impinging against the strip the circulated atmosphere is ultimately induced to return to the fan by the suction immediately upstream of the fan from whence it is again circulated to the plenum chamber. A cooling coil is usually inserted in the path of the recirculated atmosphere, normally either immediately upstream or immediately downstream of the recirculation fan.

@ne of the principal defects of such a system lies in the fact that the plenum chamber normally extends substantially completely across the width of the strip with no provision to control the pattern of atmosphere discharge with respect to the width of the strip. As is pointed out in the aforesaid Patent 2,983,497 to Dailey, lr., it is very important to control the edge-center-edge emperature pattern in a strip being rapidly cooled to safeguard against the problem of wrinkled or wavy edges. Heretofore, it has not been possible to regulate the pattern of atmosphere discharge from the plenum across the width of the strip to obtain proper edge-centeredge temperature control.

Another defect of the prior art systems lies in the fact that at least some, and usually all, of the strands of strip are impinged upon on one side by jets of atmosphere circulated by one fan and on the other side by jets of atmosphere circulated by another fan. Consequently, if one of the fans fails the plenum through which it cir- Mlce culates atmosphere will become dead and the strip will be impinged upon by jets on only one side. Without the olfsetting force of jets impinging on the other side of the strip the strip will be driven toward the dead plenum chamber. Physical contact of the strip with the dead plenum may cause marring or scratching of the strip, damage to the dead plenum, and/or rupture of the strip.

It is, therefore, the object of this invention to provide improved jet cooling apparatus for convectively cooling a heated continuously moving metal strip, the improved apparatus being free from the aforementioned and other defects of prior art jet cooling systems.

For a further consideration of what is believed to be novel and inventive, attention is directed to the following portion of the specification, the drawing, and the appended claims.

In the drawing:

FiG. l illustrates an elevational sectional View of an embodiment of apparatus constructed in accordance with this invention taken on line l-l of FlG. 4.

FlG. 2 is a sectional View taken on line 2 2 of llG. l. FlG. 2, which is drawn at a somewhat larger scale than the other figures, and which shows certain details which have been omitted from the other figures for the sake of clarity.

PEG. 3 is a sectional view taken on line 3 3 of FlG. 2.

FIG. 4 is a sectional View taken on line 4 4 of FlG. l.

FIG. 5 is a fragmentary sectional view taken on line 5 5 of FlG. l.

FIG. 6 is a fragmentary sectional View taken on line 6 6 of PIG. 1.

FlG. '7 is a fragmentary view showing an alternative mode of constructing the wind distributing boxes of the anparatus.

FlG. 8 is a sectional view taken on line 8 8 of FIG. 7.

As best illustrated in FlG. 1, a strip of sheet metal S enters cooling chamber ll through an inlet port l2 at the charging end thereof. Strip S will normally enter cooling chamber il from a first cooling chamber (not shown) where it will have been partially cooled from a higher temperature to which it had, in turn, been previously heated for metallurgical purposes. Chamber lll is defined by wall means comprising end walls i3 and ld, roof wall l5, bottom wall lo, and side walls i7 and l (FlG. 2). Strip S is advanced from inlet port l2 to outlet port i9 in a number of vertical passes or strands such as strands 2l-25, which follow the passlines of the chamber formed by successive generally vertical planes extending between successive lower turning rollers 2'7-29 and upper turning rollers Sli-33. (The passline followed by strand 25 is formed by a vertical plane extending between upper turning roller 33 and outlet port i9.)

A protective atmosphere is generally maintained within chamber ll by continually adding a suitable atmosphere thereto from a source, not shown, through one or more atmosphere inlets, not shown. An atmosphere which has been proven to be well suited for such applications is a hydrogen containing nitrogen atmosphere substantie ly free from oxygen and oxides of carbon. Such an atmosphere can be satisfactorily produced by means of apparatus described in United States Patent 2,786,741 to Huebler and Boggs. A roll-seal sealing device 34 of conventional construction is disposed in atmosphere sealing relationship with outlet port i9 to minimize atmosphere leakage therethrough. lnlet port l2 normally communicates with a prior cooling chamber in which a similar atmosphere is maintained. Hence it is normally not necessary to provide sealing means in conjunction with inlet port l2.

Associated with cooling chamber ll are a plurality of individual atmosphere recirculat'ng and cooling units such as units and 36. Each recirculating and cooling unit comprises a housi .-g 37 disposed along the side of the cooling chamber. rihe housings of alternate recirculating and cooling units are disposed on opposite sides of the the cooling chamber as is shown in FIG. 4. The purpose of this construction is to provide space alongside each recirculating and cooling unit for convenient accessibility to the com onents thereof. Located within each housing 37 is the impeller portion 3S of a an assembly powered by motor means indicated schematically at The rotation of impeller 3.2 causes a stream of atmosphere to circulate from the cooling chamber, through the housing, and back to the cooling chamber. Cooling means such as cooling coil having Contact surface portion i3 are disposed within housing 37 in the path of the stream of atmosphere circulating therethrough. A stream of coolant (preferably water) is added to cooling coil 42 by means of water inlet id and passes through Contact surface portion 43 in indirect heat transfer relationship with the stream of atmosphere. rl`he coolant is ultimately withdrawn through water outlet 45'.

After having been cooled the atmosphere is returned from housing 37 to cooling chamber lll and is received therein by means of a plenum chamber indicated generally at d6. Plenum chamber 46 comprises a plurality of separated segments disposed intermediate successive passlines of the cooling chamber in such a manner that it is adapted to separate a number of passlines equal to one less than the number of segments of the plenum chamber. In the illustrated embodiment plenum chamber 46 is conn structcd of three segments comprising end segments 47 and 49 and intermediate segment 4S. Disposed immediately adjacent an end segment d'7 of one plenum chamber is an end segment 49 of the plenum chamber associated with the next adjacent atmosphere cooling and recirculating unit. lt is to be understood that each plenum chamber do could, within the ambit of this invention, be constructed with a plurality of intermediate segments corresponding to intermeditae segment 48. Likewise, each plenum chamber could be constructed of only two end segments corresponding to segments 47 and i9 without any intermediate segment corresponding to segment 48. rThis latter construction would be the preferred construction were it desired to adapt this invention to a single pass strip cooling unit such as that described in Canadian Patent 613,946.

The atmosphere which is circulated into segments 47, 4S, and 49 of plenum chamber 416 from housing 37 is distributed therefrom into cooling contact with the heated strands of strip passing through the cooling chamber ill along the passlines thereof by means of a plurality of distributing boxes which extend vertically from each segment along the passlines of the chamber toward the remote regions thereof. ln the construction illustrated each of the plenum chambers is located at a point intermediate the top and bottom of the cooling chamber and it is therefore necessary to provide both upper and lower distributing boxes extending from each of the plenum chamber segments toward, respectively, the upper and lower reaches of the cooling cham er. It is to be understood, however, that in some embodiments, such as in single-pass strip cooling arrangement of the type illustrated in the aforementioned Canadian Patent 613,946, it will be preferable to locate the plenum chamber either at the bottom or at the top of the cooling zone in which case there will be only a single set of distributing boxes associated with each segment of the plenum chamber and extending vertically therefrom either upwardly or downwardly as required.

in the construction illustrated each end plenum charnber segment i7 is equipped with a set of upwardly extending distributing boxes including end distributing boxes 51 and 52 and at least one intermediate distributing box 53 and a set of lower distributing boxes including end distributing boxes 5d and 55, and intermediate distributing CII box 5d; each end plenum chamber segment 49 is equipped set of upper distributing boxes including end distributing boxes 6d and 65 and intermediate distributing box and a sct of lower distributing boxes including end distributing boxes 67 and and intermediate distributing box 69; and each intermediate plenum chamber segment is equipped with a set of upper distributing boxes including end distributing boxes 57" and 53 and intermediate distributing box 59 and a of lower distributing boxes comprising end distributing boxes el and 62 and an intermediate distributing box 63.

The individual distributing boxes above described, which may be readily fabricated from metal plate according to known techniques, are of generally rectangular configuration having two sides or faces extending in a plane parallel to the passlines of the cooling chamber. The thickness, as measured along the horizontal dimension which extends perpendiculariy to the passlines of the cooling chamber, of each distributing box in a set extending from an intermediate plenum chamber segment is approximately twice as great as the thickness of cach distributing box in a set extending from an end plenum chamber segment. This construction makes it possible to insert an end plenum chamber segment 9, from one cooling and recirculating unit and the distributing boxes in the set or sets associated therewith, together with an end plenum chamber segment 47 of the next adjacent cooling and recirculating unit and the associated distributing boxes between two adjacent passlines of the furnace.

The use of at least three distributing boxes in each set is necessary to provide means to overcome the inherent tendency of the edges of a strip to cool more rapidly than `the center thereof, a phenomenon which gives rise to an undesirable condition of wrinkled or wavy edges in the finished product in the manner explained in the aforesaid Patent 2,983,497 to Dailey, Jr. When three or more distributing boxes are used in each set the tendency for the edges of the strip to over-cool may be combatted by equipping each of end distributing boxes 5l, 52, 5d, 55, 57, 58, 6l, 62, 6d, 65, 67, and 63 with damper means to throttle the ow of cooling fluid therefrom such as a butterfly damper 7l (shown only in FlG. 2) located within each end distributing box and rigidly attached to a shaft 72 which extends therefrom outwardly from the cooling chamber 1l where it is connected to a handle 73 to permit manual adjustment thereof.

Another factor which is of some importance in attaining proper edge-center-edge temperature control is the proper sizing, with respect to each other, of the width of each of the distibuting boxes as measured horizontally along the faces of each distributing box which are disposed parallel to the passlines of the cooling chamber. It is preferred that the width of each intermediate distributing box be from 1.0 to 2.0 times greater than the width of each of the end distributing boxes in the same set which, in turn, should be equal to one another.

In assembling the various distributing boxes it is important to provide expansion means to compensate for the vertical thermal expansion which will occur because of the exposure of the elongate distributing boxes to heated strands of strip and because of the contact of the exterior of the boxes with atmosphere that has been heated by virtue of its contact with the strip. lt is also desirable to provide individual expansion means for each distributing box so that the individual distributing boxes in each set may expand or contract independently or one another. in providing expansion means for any elongate member it is important to construct the means in such a manner that they will allow expansion only in the direction required and in no other direction. It is also important to permanently secure the elongate member at a given point while allowing other portions thereof the freedom of expansion. it is also important to judiciously i n. Se.

select .the optimum point for securing the elongate member.

In the present invention each of the distributing boxes is permanently secured at the end thereof that is adjacent to the plenum chamber segment from which the distributing box extends, as by joining the end to the plenum chamber segment by Welding. Expansion guides, such `as that illustrated generally at 74 of FIGS. 2 and 3, are provided 4at one or more points :along the length of each set of distributing boxes. Each expansion guide 74 comprises a horizontal bar 75 extending across the cooling chamber from side wall 17 to side wall 18 through each of the `distributing boxes in a given set. Horizontal bar 75 is secured to side wall 17 and side wall 18 by permanently securing it to each of internal and external bearing plates 76 and 77, as by welding. Bearing plates 76 and 77, in turn, are secured to the respective side wall of the cooling zone such as by welding or by bolting thereto.

Disposed within each end `distributing box and each intermediate distributing box are, respectively, elongate sleeve members 78 and 79, each of which extends from side to side of the particular distributing box in which it is disposed and each of which is adapted to surround a por-tion of horizontal bar 75. Each of the distributing boxes is provided with elongate slots in the side walls thereof through which the sleeve member is inserted. When each sleeve member is in place it should, preferably, be secured to the side wall of the distributing box by means of a continuous weld to prevent the cooled atmosphere within the distributing box from exiting through the aforesaid elongate slots. Each of the elongate sleeve members 78 and 79 has a height dimension h and a width dimension w. The sleeves are so disposed that dimension h, which is considerably larger that the external diameter "d f horizontal bar 75 (or the vertical thickness of a non-circular bar), extends in -a vertical directicn and dimension "w, which is -only slightly larger than the vdiameter d of horizontal bar 75 (or the horizontal thickness of a non-circular bar) extends in a horizontal direction. Thus, there is considerable vertical clearance between sleeves 7 8 :and 7 9 respectively and horizontal -bar 75 (specical-ly, dimension h less dimension d) and only slight horizontal clearance therebetween. The liberal vertical clearance, which preferably ought to be at least l for each ilyseparating the expansion guide, from the restrained end of the distributing box, allows .each distributing box to freely expand and contract in response to changes in temperature both with respect to horizontal bar `75 and with respect to other distributing boxes. The very slight horizontal clearance, on the other hand, which may be of the order of magnitude of 1A inch or so, effectively restrains the distribution boxes from moving excessively in a horizontal direction perpendicular .to the axis of horizontal bar 75. Excessive movement of the distributing boxes in la horizontal direction parallel to the axis of horizontal bar 75 may be effectively restrained by means of retainer plates 8l attached to horizontal bar 75.

The cooled atmosphere which is circulated into the distributing boxes from the plenum chamber segments is permitted to pass therefrom in a plunality of individual streams or jets through port or nozzle means such as ports 82 whose axes are directed toward the strands of strip passing through the passlines `of the cooling chamber, and preferably at right angles thereto. Ports S2, whose presence is indicated in FIGS. l, 5, and 6 by arrows representing jets of atmosphere owing therethrough, are located in both of the passline parallel faces of the distributing boxes which extend from an intermediate plenum chamber segment and in that passline parallel face of the distributing boxes extending from an end plenum chamber segment which is disposed most proximate'ly to the distributing boxes extending from 4the -other end plenum chamber segment of the same plenum chamber.

According to the above-described placement of ports,

it can be seen that both sides of each strand of strip passing through Ithe cooling chamber ywill have jets of atmosphere circulated thereagainst from the same cooling and necirculating unit. Thus, the danger that a given `strand of strip could be exposed to the circulation of jets of atmosphere against only a single side thereof, which has heretofore been inherent in prior art jet cooling devices, has been obviated in the present invention.

The ports 32 are preferably disposed in the respective faces of the respective distributing boxes in a plurality of rows such as rows tid-lib cach of which extends in a substantially straight line horizontally across the individual distributing boxes in the respective set of distributing boxes. For optimum heat transfer efliciency it is preferred to construct the distributing boxes with equally sized ports and with uniform spacing (in a vertical direction) between the individual rows of ports. However, it is recognized that the vibration of each suspended strand, which is inherent when fluid passes thereover, tends to become more uniform as the velocity of the fluid increases until a condition of resonant-vibration, otherwise known as flutter, will ultimately occur. This condition causes large destructive forces to act on the strip and must be avoided, normally by limiting the velocity of the fluid passing thereover to sorne safe velocity less than the velocity which will cause llutter. in those instances where the desired rate of atmosphere recirculation will cause atmosphere to `llow past the strip at velocities dangerousl v close to the velocity which will cause flutter, it is possible to at least partially overcome the problem by constructing the distributing boxes with vertical non-uniform spacing of the rows of ports which may be achieved, for example, by constructing distributing boxes @-63 with a vertical spacing between the ports in row and the ports in row 86 different from the vertical spacing between the ports in row liti and the ports in row S7. The force exerted against a strand by jets of atmosphere passing from ver tically non-uniformly spaced horizontal rows of ports tends to dampen or interfere with the uniformly spaced nodes characteristic of resonant vibration. The net effect is to increase the fluid velocity at which resonant vibration will occur and thereby increase the safe velocity at which fluid can be passed over the strip.

An alternative mode of construction of wind distributing boxes is illustrated in fragmentary FlGS. 7 and 8 wherein are illustrated wind distributing boxes numbered i555, l, 16d, ldd' and led which correspond, rcspectively, to wind distributing boxes 523, 5), ed, 65 and 6d of FlGS. 1 6. The wind distributing boxes of FGS. 7 and 8 differs from the wind distributing boxes of FlGS. lin the construction of the port means from whence the cooling fluid is circulated into cooling contact with the strands of strip within the cooling chamber. Each of the distributing boxes of FiGS. 7 and 8 has port means comprising a plurality of horizontally extending slots such as slots i8?) and las. Associated with each of slots 533 and 184 are ilow dei ecting means comprising upper baiie lll and lower bafe M2. Raffles lll and il?. are disposed within the respective wind distributing boxes adjacent the respective longitudinally extending slots; upper balde ill being disposed adjacent the upper limit of each slot and lower baffle lli being disposed adjacent the lower limit of each slot. Each of baffles lll and M2 is disposed longitudinally in a horizontal direction and is disposed transversely in a direction which is removed from the horizontal by an angle a in a direction toward which the adjacent strand of strip is travelling (as indicated by arrowheads on fragmentary portions of strands 25 and The purpose of constructing the wind distributing boxes in this manner is to impart a component of motion to the jets issuing therefrom which will result in countcrflow heat exchange from the strip to the cooling fluid. ln achieving this result some liberality is permitted in the selection of the angle a. We prefer that angle a be approxi- 7 mately 3j but it is permissible to use smaller angles or larger angles up to 50 or so;

Another ot the features of the present invention lies in therarrangement of the elements thereof in a manner to inhibit the infiltration of air from the surrounding atmosphere intov the cooling chamber. Even when the nest construction techniques are employed it is not possible to construct a chamber such as a cooling chamber @il which will becompletely gas tig/lit., if only because of imperfect or cracked welds dr leaky bolted iittings.- Hence, the only feasible way to combat the problem of air' iti-v ltration into such a cooling chamber is to maintain the pressure of the protective atmospherey within the cooling chamber at some pressure at least slightly in excess of atmospheric pressure. Where the cooling chamber defines a protective atmosphere tiow circuit including a fan, which inherently operates to compress the recirculating atmosphere, it will be elativeiy simple to prcssurize all po. tions of the chaml er except that portion which defines the atmosphere llow path immediately upstream of the fan. The region immediately upstream of the fan is often culled thc suction side of the fari and will normally be at some sub-atmospheric pressure. We have found that the only feasible way to safeguard against inhitration of air' into such a sub-atmospheric region is to physically isolate or surround the region with a separate region wherein the pressure is maintained at `a super-atmospA eric valuti.;l

ln the illustrated embodiment of the presentinvention it may be seen that the protective atmosphere within chamber il, by virtue of the pressure imparted thereto by the rotation of impeller portion 38 of fan assembly 39, will be at some super-atmospheric pressure in virtually all portions of the chamber except in short conduit portion $3 deiined by generally cylindrical wall means 39. lnltration of air into conduit portion 81B, which defines the path for Spent circulated atmosphere to flow from cooling charnber lil to iinpeller .'53, may be prevented by surrounding chamber 38 with a pressurized annular chamber Sil which is dened on the ends by annular plates 92 and 93 and on its internal periphery by wall means S9. Annular chamber 9i. may be readily pressurized by locating one or more ports 94 in annular plate 93 thereby allowing some of the pressurized atmosphere from the region immediately downstream of impeller 3? to flow thereinto. ln addition it is possible to partially compensate for the subatmospheric pressure that exists within conduit 8S by locating one or more ports 95 in cylindrical wall means S9 to allow pressurized atmosphere to bleed into conduit S3 from pressurized annular chamber 91.

Another region of the cooling chamber which is vulnerable to the inhltration or because of the existence of a sub-atmospheric pressure condition is the region intermediate impeller portion T13 of fan assembly 39, and rear wall portion itil of housing 37, a region denoted by numeral L33. lt has been found that infiltration of air into this region may be combatted by means of a diaphrarn 96 located therein having a truste-conical surface portion 97 and an annular surface portion 93. Frustoconical surface portion Y? o diaphragm 93 tits closely to rotating shaft portion 99 of tan assembly 39 and retards iiow along shaft portion Diaphragm It is also disposed within housing 37 in such a manner that annular surface portion is disposed a small fixed distance (such as 1A inch) from rear wall portion 1 fl of housing 37. To provide the correct small spacing a number of pieces of shim stock ttl?. may be located at periodic intervals around annular surface portion 93 of diaphragm 9115. rlhe small spacing between annular surface portion 93 and rear wall portion allows some protective atmosphere to flow thereinto from a portion of the housing where the pressure of the protective atmosphere is super-atmospheric. Hence, the use of a diaphragm 96 in the manner described permits the creation of a region 3161i containing protective atmosphere at super-atmospheric pressure in- ,termediatc region E63 and rear wall portion itil. rThus,

any leakage along shaft portion 99 of ian asset'ibly 3S past conical surface portion 97 of diaphragm 6 will be the leakage of protective atmosphere from region M34, and the danger of the infiltration of air into region 103 is thereby bviated.

The best mode' known to us to carry out this invention has been described in tct'rns suliiciently full, clear, Concise, and exact as to enable any person skilled in the art to practice the invention. However, it is understood that various modifications will be readily apparent to a skilled artisan without departing from the scope of the invention which is defined only by the appended claims.

1. Strip cooling apparatus comprising, in combination.' wall means deiining a cooling chamber; circulating means for circulating a stream of cooling fluid into said chamber; distributing box means in fluid communication with i circulating means', said distributing7 box means comprising two sets of distributing boxes disposed within said cham-l ber, said sets of distributingv boxes extending generally' vertically and being disposed generally parallel to each Y- .id being separated from cach other, each set of distirsuting boxes comprising two end distributing boxes and at least one intermediate distributing box disposed intermediate said end distributing boxes, each of said distributing boxes being formed by wall means comprising ports adapted to permit the flow of cooling iuid from the dis-7 tributing box in a direction having a substantial compo entof motion normal to the other of the sets of distributing boxes; and roller means for conveying a strand of strip through said cooling chamber intermediate said sets of distributing boxes, whereby cooling fluid is circulated from said circulating means into said distributing boxes and from said distributing boxes through said ports toward said strip in a direction having a substantial component of motion directed vertically thereto.

2. Apparatus according to claim 1 and further comprising means associated with said ports to deect the ow of cooling fluid therethrough from the horizontal by an angle not in excess of 45 3. Apparatus according to claim 2 wherein said means comprises battles within said distributing boxes adjacent each of said ports.

4. Apparatus according to claim l wherein said ports are spaced from each other at vertically non-uniform intcrvals.

5. Apparatus according to claim l and further comprising damper means associated with each of the end distributing boxes in each set of distributing boxes whereby the circulation of cooling iiuid into said end distributing boxes may be throttled.

6. Apparatus according to claim l and further Comprising conduit means for passing a stream 0i cooling iluid from said cooling chamber to said circulating means and cooling means adapted to cool the stream of cooling fluid from said chamber whereby cooling fluid may be continuously recirculated from said circulating means to said chamber by way of said sets of distributing boxes and back to said circulating means.

7. Apparatus according to claim l wherein one end of each distributing box in a set is restrained the other end of each distributing box in a set is free to expand and contract in response to thermal change and further comprising expansion guide means disposed longitudinally of said distributing box means from said restrained end, said expansion guide means comprising an elongate sleeve disposed within each distributing box in a set, with each of the elongate sleeves disposed within each distributing box in a set being disposed in horizontal alignment with each other, and a horizontal bar extending from opposite wall means of the Cooling chamber, said horizontal bar passing successively through the elongate sleeve of each distributing box in a set, each sleeve having a height dimension and a dimension and being disposed with the height witun dimension extending vertically and the width dimension extending horizontally, the height dimension of each sleeve being considerably larger than the vertical thickness of said horizontal bar and the width dimension being only slightly larger than the horizontal thickness of said horizontal bar whereby t permit free vertical movement of each of said distributing boxes while simultaneously restraining horizontal movement in a direction perpendicular to the axis of said bar.

8. Apparatus according to claim 7 and further comprising two retainer plates disposed normally to said horizontal bar and securely attached thereto in a manner to restrain horizontal movement of the distributing boxes in a direction parallel to the axis of said bar.

9. Strip cooling apparatus comprising, in combination: wall means defining a cooling chamber; a number of recirculating and cooling units, each unit comprising a housing disposed toward one side of said chamber; cooling means within said housing; fan 'means adapted to circulate a stream of cooling fluid from said chamber through said housing past said cooling means and back to said cooling chamber; plenum chamber means to receive the stream of cooling fluid recirculated into said chamber `from said housing, said plenum chamber means comprising a plurality of individual separated plenum chamber lsegments, said plurality comprising two end plenum chamber segments and an integral number equal to N of intermediate plenum chamber segments disposed intermediate said end plenum chamber segments; roller means comprising a plurality of upper turning rollers and a plurality of lower turning rollers for conveying strip to and fro through said cooling chamber in a plurality of generally vertical strands including a number of strands equal to N plus one, said strands passing, successively, intermediate successive segments of said plenum chamber means and generally parallel thereto; and distributing box means comprising at least one set of distributing boxes associated with each of said end and said intermediate plenum chamber segments and in fluid flow relationship therewith, each set of distributing boxes comprising at least three distributing boxes disposed in side by side relationship longitudinally of the plenum chamber segment with which said set is associated, and including two end distributing boxes and at least one intermediate distributing box disposed between said end distributing boxes, each of said distributing boxes being formed by Wall means comprising a ported face which is disposed generally parallel to the other sets of distributing boxes whereby cooling fluid is circulated into said plenum chamber means from said cooling and recirculating unit and from said plenum chamber means into said distributing box means and from said distributing box means into cooling contact with said strands of strip through said port means.

10. Apparatus according to claim 9 wherein N is equal to one.

11. Apparatus according to claim 9 wherein the housings of adjacent recirculating and cooling units are disposed on opposite sides of the cooling chamber.

l2. Apparatus according to claim 1l wherein an end plenum chamber segment of the plenum chamber means associated Iwith a cooling and recirculating unit and an end plenum chamber segment tof the plenum chamber 10 means associated with the next adjacent cooling and recirculating unit are disposed between successive strands of strip.

13. Apparatus according to claim l() wherein each of the distributing boxes in a set associated with an end plenum chamber segment is provided with port means in t-hat face which is disposed more proximately to the set of distributing boxes associated with the other plenum chamber segment of the same plenum chamber means and wherein each of the distributing boxes in a set associated -with an intermediate plenum chamber segment is provided with port means in both of said faces.

14. Apparatus according to claim 13 wherein said port 'means comprises a plurality of horizontal rows of ports.

15. Apparatus according to claim 14 wherein said horizontal rows of ports are vertically non-uniformly spaced.

16. Apparatus according to claim 9 wherein the wall means Vdefining said cooling chamber comprises a roof wall and a bottom wall and wherein each of said plenum chamber means is disposed at a point intermediate said top wall and said bottom Wall and wherein said distributing box means comprises two sets of distributing boxes associated with each. of the end and the intermediate plenum chamber segments of each plenum chamber means said two sets consisting of an upper set and a lower set, said upper set extending vertically from the respective plenum chamber segment toward the roof wall and said lower set extending from the respective plenum chamber segment toward the bottom wall.

17. Apparatus according to claim 9 wherein said housing comprises a backplate and wherein said fan means comprises an impeller disposed within said housing and a shaft portion attached to said impeller and extending therefrom outwardly from said housing through said backplate and lfurther comprising a generally annularly shaped diaphragm adapted to closely circumpose said shaft portion disposed within said housing intermediate said impeller and said backplate, said diaphragm having an annular surface portion disposed a small distance from said backplate and parallel thereto whereby cooling fluid will flow from said housing into the space between said diaphragm and said backplate and block the infiltration of air into said housing along said shaft portion.

18. Apparatus according to claim 17 and further comprising wall means within said housing dening a conduit portion through which cooling iluid flows from said cooling chamber to said impeller, and an annular chamber disposed within said housing circumposing said conduit portion, said annular chamber being defined by wall means having ports to permit the ingress of pressurized cooling fluid from that region of said housing downstream of said impeller.

References Cited in the file of this patent UNITED STATES PATENTS 1,987,410 Moore Jan. 8, 1935 2,023,285 Otis Dec. 3, 1935 2,144,919 Gautreau Ian. 24, 1939 2,693,353 Vaughan Nov. 2, 1954 

1. STRIP COOLING APPARATUS COMPRISING, IN COMBINATION: WALL MEANS DEFINING A COOLING CHAMBER; CIRCULATING MEANS FOR CIRCULATING A STREAM OF COOLING FLUID INTO SAID CHAMBER DISTRIBUTING BOX MEANS IN FLUID COMMUNICATION WITH SAID CIRCULATING MEANS, SAID DISTRIBUTING BOX MEANS COMPRISING TWO SETS OF DISTRIBUTING BOXES DISPOSED WITHIN SAID CHAMBER, SAID SETS OF DISTRIBUTING BOXES EXTENDING GENERALLY VERTICALLY AND BEING DISPOSED GENERALLY PARALLEL TO EACH OTHER AND BEING SEPARATED FROM EACH OTHER, EACH SET OF DISTRIBUTING BOXES COMPRISING TWO END DISTRIBUTING BOXES AND AT LEAST ONE INTERMEDIATE DISTRIBUTING BOX DISPOSED INTERMEDIATE SAID END DISTRIBUTING BOXES, EACH OF SAID DISTRIBUTING BOXES BEING FORMED BY WALL MEANS COMPRISING PORTS ADAPTED TO PERMIT THE FLOW OF COOLING FLUID FROM THE DISTRIBUTING BOX IN A DIRECTION HAVING A SUBSTANTIAL COMPONENT OF MOTION NORMAL TO THE OTHER OF THE SETS OF DISTRIBUTING BOXES; AND ROLLER MEANS FOR CONVEYING A STRAND OF STRIP THROUGH SAID COOLING CHAMBER INTERMEDIATE SAID SETS OF DISTRIBUTING BOXES, WHEREBY COOLING FLUID IS CIRCULATED FROM SAID CIRCULATING MEANS INTO SAID DISTRIBUTING BOXES AND FROM SAID DISTRIBUTING BOXES THROUGH SAID PORTS TO- 